A011365 Reciprocal of g.f. for A007863.

1, -2, -3, -11, -49, -244, -1301, -7265, -41945, -248357, -1499838, -9202478, -57204263, -359491066, -2280171089, -14578108497, -93850280001, -607856133804, -3958143058643, -25897182540675, -170164359751174, -1122422557526850, -7429480035700452

Offset: 0

Author

N. J. A. Sloane

Keywords

• sign

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..500

Crossrefs

Cf. A007863.

Programs

PARI

a(n) = if (n==0, 1, if (n==1, -2, -sum(i=0, n, binomial(n+i-2,n-2)*binomial(n+i-1,n-i))/(n-1))); \\ Michel Marcus, Dec 29 2018

Formula

a(n) = -(Sum_{i=0..n} binomial(n+i-2,n-2)*binomial(n+i-1,n-i))/(n-1), n>1; a(0) = 1, a(1) = -2. - Vladimir Kruchinin, Feb 15 2013